(Adaptive Control of Thought—Rational) is a theory of human cognition. The ACT-R theory has a computational implementation as an interpreter of a special coding language. The interpreter itself is written in Common Lisp. Th ACT-R software distribution uses Tcl/Tk for GUI and scripting interface.

is an architecture for planning and learning, including explanation-based learning, partial evaluation, experimentation, graphical knowledge acquisition, automatic abstraction, mixed-initiative planning, case-based reasoning and a number of real-world domains. It is written in Lisp with a Tcl/Tk GUI.